In the process of vehicle development, the unsteady simulation of thermal management system is very important. A 3D-CFD calculation model of vehicle thermal management is established, and simulations were undertaken for uphill with full loads operations condition. The steady results show that the surface heat transfer coefficient increases to the quadratic parabolic relationship. The unsteady results show that the pulsating temperatures of exhaust and external airflow are higher than about 50°C and lower than 10°C, respectively, and the heat dissipating capacities are higher than about 11%. Accordingly, the conversion equivalent exhaust velocity increased by 1.67%, and the temperature distribution trend is basically the same as unsteady results. The comparison results show that the difference in the under-hood should be not noted, and that the predicted exhaust system surface temperatures using steady velocity equivalent method are low less 10°C than the unsteady results. These results show the steady velocity equivalent method can be used to predict the unsteady heat transfer effect of vehicle thermal management system, and the results obtained by this method are basically consistent with the unsteady results. It will greatly save computing resources and shorten the cycle in the early development of the vehicle thermal management system.

在车辆开发过程中，热管理系统的非定常模拟非常重要。建立了车辆热管理3D-CFD计算模型，并对满载上坡工况进行了仿真。稳态结果表明，表面传热系数呈二次抛物线关系增大。非稳态结果表明，排气和外部气流的脉动温度分别高于约50°C和低于10°C，散热能力高于约11%。相应地，转化当量排气速度提高了1.67%，温度分布趋势与非稳态结果基本一致。比较结果表明，发动机罩下的差异不应被注意到，并且利用稳态速度等效方法预测的排气系统表面温度比非稳态结果低10°C。结果表明，稳态速度等效法可以用来预测车辆热管理系统的非稳态传热效果，并且该方法得到的结果与非稳态结果基本一致。它将在车辆热管理系统的早期开发中大大节省计算资源并缩短周期。